This is off topic in regard to OP's post on his model 1899 carbine, but, FWIW:

The, so called, "school rifles" and "Philippine Constabulary rifles" were made from model 1899 (and updated model 1898) carbines, fitted to modified rifle stocks and front barrel-bands.

IIRC - Some Philippine Constabulary rifles, altered at the Manila Ordnance Depot, could have been made from model 1896 carbines.

The carbine sights were on these arms before alteration and would be correctly sighted for the, still 22 inch, barrels.